It is always pleasing for authors to find out that they have readers in far flung places. It was therefore surprising but gratifying to see a picture of a battered copy of a French translation of a book I wrote calledThe Jihadis Return abandoned by Isis fighters, along with suicide vests and homemade explosive devices, as they retreat from their last enclaves in Deir ez-Zor province in eastern Syria.

The book was written in 2014 when Isis was at the height of its success after capturing Mosul, and was sweeping through western Iraq and eastern Syria. I described the Isis victories and tried to explain how the movement had apparently emerged from nowhere to shock the world by establishing the Islamic State, an entity which at its height ruled 8 million people and stretched from the the outskirts of Baghdad to the Mediterranean.

A picture of the book, Le Retour des Djihadistes, was tweeted by Quentin Sommerville, the intrepid BBC Middle East correspondent, who is travelling through the deserts of Deir ez-Zor and reporting what may be the last pitched battles fought by Isis. The book had presumably belonged a French-speaking Isis fighter: many Isis volunteers came from Tunisia, Algeria and Morocco, as well as from France itself, and may now be trapped in this corner of Syria.

But is this truly the last round for Isis? The Islamic State no longer controls territory, but will it live on as an ideology inspiring a core of fanatical believers who will seek to rise again? They know that the US wrongly declared that al-Qaeda in Iraq, the precursor of Isis, was dead and buried in 2007-08. Isis hopes to repeat its previous resurrection by waiting for its many enemies to relax their pressure and to fall out among themselves.

The book found in Deir ez-Zor tried to explain how Isis had escaped decisive defeat last time around, so an Isis fighter might have been interested in reading it in the hope of finding out how his movement might survive today. I wrote that al-Qaeda in Iraq was never quite as dead as people imagined: I had Iraqi business friends who were forced to pay it protection money in Mosul even when it was at the nadir of its fortunes. It was notorious that the Iraqi army of the day was a corrupt money-making racket with “ghost” battalions, from which money for non-existent soldiers, their fuel and supplies was siphoned off by crooked officers. I thought that Iraqi politicians were exaggerating when they told me that the army was never going to fight but they turned out to be right.

The most important factor reopening the door to Isis was the civil war in Syria after 2011, where the armed opposition was rapidly taken over by jihadis directed by battle-hardened commanders sent by al-Qaeda in Iraq. Well-organised fanatics willing to die for a cause and experienced in warfare will always dominate their own side when serious fighting gets under way. I portrayed Isis as an Islamic version of the Khmer Rouge and, like their Cambodian counterparts, they systematically committed atrocities to terrify and demoralise their opponents.

Could all this happen again, or are we looking at the final chapter of the Isis nightmare as the group is cornered in Syria and driven into the desert wastes of Iraq? Perhaps they will survive in small numbers, depending what resources in men and materials they preserve in their hideouts. Occupying armies almost invariably alienate local populations and a resurgent Isis might be able to exploit this. Their reputation for savagery was such that they can give the impression that they are still in business by carrying out a few limited attacks.

I was in Baghdad last year when there were some gruesome killings and kidnappings on the main road north to Kirkuk. These were pinpricks compared to the massacres of 2014, but they were enough to produce extreme nervousness in the capital, where people spoke with real fear of Isis being reborn.

I do not believe that this is going to happen because Isis no longer has the advantage of surprise as it did in the past. The surprise in 2014 was greater than it should have been because Isis had been winning local battles and taking territory for some time. I had made Abu Bakr al-Baghdadi, the Isis leader, the Independent Middle East man of the year for 2013. But a consequence of the unexpected emergence of Isis five years ago is that nobody is ever again going to underestimate them. The Iraqi army of today is very different from the old and recaptured Mosul after overcoming ferocious Isis resistance.

Isis could and probably will revert to guerrilla warfare and high-profile terror attacks to show that it is still an enemy to be feared. The pictures of the suicide vests studded with ball bearings from Deir ez-Zor show that suicide bombing is still an essential part of their tactics. But Isis no longer has the resources of the well-organised Islamic State to recruit, train and finance suicide bombers on the industrial scale of the past.

An invasion of northeast Syria by Turkey, which denounces the Kurdish YPG soldiers fighting Isis with American support as terrorists, could relieve the pressure on the jihadis. Another danger is that former Isis and al-Qaeda fighters will be absorbed into the Arab militia units allied to Turkey, which have already carried out ethnic cleansing of Kurds and Yazidis from the Kurdish majority Syrian province of Afrin that Turkish-led forces captured last year.

Governments have by-and-large learned about the threat posed by Isis and are not going to allow it to rise again. But, in another important sense, the US, UK and allied governments have learned nothing from their disastrous actions in the Middle East and North Africa over the past 20 years which opened the door to Isis. During this period, they repeatedly denounced dictatorial but powerful national leaders – Saddam Hussein, Muammar Al Gaddafi, Bashar al-Assad – as illegitimate and instead supported shadowy opposition figures with whom they were friendly as the true leaders of their countries.

The result was invariably disastrous: in July 2011, to take but one example, the British government announced that it was recognising the rebel council in Libya as the sole governmental authority there. But the rebels turned out to have little real power other than that provided by Nato, making it inevitable that a post-Gaddafi Libya would collapse into criminalised anarchy.

Fast forward to Venezuela this week when the US, along with the UK, Canada and a bevy of South American states, declared that the opposition leader Juan Guaido is the country’s legitimate ruler, replacing President Maduro.

The UK foreign secretary, Jeremy Hunt, said the hitherto little known Guaido was the right person to take the country forward, though there is no obvious reason to think so. On the contrary, we are seeing the same sort of crude imperial overreach producing failed states and chaos that brought calamity to Afghanistan, Iraq, Libya and Yemen. The terrible lesson of the rise and fall of Isis has taught leaders in Washington and London very little.